Packet communication method, controller and mobile station

ABSTRACT

A packet communication method of the present invention includes establishing a radio layer  2  connection based on a radio layer  2  protocol between a mobile station and a controller device, determining a transmission timing of a received data packet based on a quality of service set in the data packet, and multiplexing, at the determined transmission timing, the data packet into a radio layer  2  protocol data unit of a fixed length which is transmitted and received on the radio layer  2  connection.

TECHNICAL FIELD

The present invention relates to a packet communication method, acontroller device, and a mobile station, for performing packetcommunication using radio access technology.

BACKGROUND ART

The Universal Mobile Telecommunication System (UMTS) standardized in the3rd Generation Partnership Project (3GPP) has been known as athird-generation radio communication system for implementing packetcommunication using radio access technology.

FIG. 1 shows the configuration of a conventional radio communicationsystem including a UMTS network. As shown in FIG. 1, base stations BS, aradio network controller RNC, a subscriber node SGSN (Serving GPRSSupport Node), and a gateway node GGSN (Gateway GPRS Support Node) aredisposed in the UMTS network. The UMTS network is connected to a packetcommunication network such as the Internet. Communication terminals TEsuch as personal computers (PC) can be connected to the UMTS network viamobile stations MS.

FIG. 2( a) shows a protocol stack in the conventional radiocommunication system. FIG. 2( b) shows the configuration of a Radio LinkControl (RLC) connection and GPRS Tunneling Protocol (GTP) connectionsestablished in the conventional radio communication system.

As shown in FIG. 2( a), in the conventional radio communication system,an RLC connection based on the RLC protocol is established between themobile station MS and the radio network controller RNC.

A GTP connection is established between the radio network controller RNCand the subscriber node SGSN. A GTP connection based on the GTP protocolis established between the subscriber node SGSN and the gateway nodeGGSN.

Here, in the radio network controller RNC, the RLC connectionestablished with the mobile station MS is associated one-to-one with theGTP connection established with the subscriber node SGSN.

In the subscriber node SGSN, the GTP connection established with theradio network controller RNC is associated one-to-one with the GTPconnection established with the gateway node GGSN.

Radio communication systems generally need to handle communicationswhich require various qualities of service (QoS), from communicationswhich require real time such as voice communications and videocommunications, to communications which permit some delay such ase-mails.

For this, it is known to perform QoS control in a transport technologysuch as the Asynchronous Transfer Mode (ATM) technology or the IPtechnology, so as to meet QoS requirements such as an allowabletransmission delay and an allowable packet loss in each communication.

In the ATM technology, for example, various traffic managementtechniques are defined, so that functions of dealing with various QoSrequirements, from guaranteed-bandwidth services to best-effortservices, can be used. In the IP technology, QoS control functions suchas Differentiated Services and Integrated Services can be used.

However, when a plurality of communications are multiplexed to an RLCconnection as shown in FIG. 2( b), that is, when a plurality of datapackets are multiplexed and loaded into RLC-PDUs (Protocol Data Units),the data packets are handled as having the same QoS requirement at anATM connection (or at an IP tunneling connection, an MPLS connection orthe like), and there occurs the problem that QoS control cannot beperformed on each communication.

To solve this problem, it has been conceived that, as shown in FIG.2(C), in the conventional radio communication system, the mobile stationMS creates multiple “Packet Data Protocol (PDP) contexts” for datapackets having different QoS requirements, according to communicationdestinations and the QoS requirements, and establishes multiple RLCconnections for the created PDP contexts.

A PDP context is a collection of information set for the subscriber nodeSGSN, the gateway node GGSN and so on before communication. The PDPcontext includes communication status information, information on QoSrequirements required in a communication, communication destinationinformation and so on.

In the conventional radio communication system, the base station BS andthe radio network controller RNC perform synchronous control at thestart of communication, for determining a transmission timing of anMAC-PDU from the radio network controller RNC to the base station BS.

In a soft handover where a mobile station MS performs communicationsthrough different base stations BS at a time, the synchronous controlallows the different base stations BS to transmit an MAC-PDU to themobile station MS simultaneously using the W-CDMA technology.

Here, the timing for the base stations BS to transmit the MAC-PDUtransmitted from the radio network controller RNC to the mobile stationMS is determined in view of a transmission delay between the basestations BS and the radio network controller RNC, a wait time due to QoScontrol and so on.

The base stations BS are configured to refer to a sequence number givento a Frame Protocol (FP) frame transmitted from the radio networkcontroller RNC, and transmit an MAC-PDU included in the FP frame of anappropriate sequence number at a transmission timing determined asdescribed above.

However, the conventional radio communication system has the problemthat a mobile station MS needs to establish a plurality of RLCconnections for data packets with different QoS requirements even forcommunication with the same communication destination, and must have thecapability of establishing a plurality of RLC connections.

Also, the conventional radio communication system has the problem that amobile station MS must perform a path change for all established RLCconnections and GTP connections at the same time, when changing acommunication path due to a handover, which results in an increasedcontrol load and reduced performance.

Also, the conventional radio communication system has the problem thatsince a wait time for a low-priority MAC-PDU is set long in the basestation BS, even when an FP frame including a low-priority MAC-PDU istransferred from the radio network controller RNC to the base station BSwith a small delay, the base station BS must wait to transmit theMAC-PDU included in the FP frame until a determined timing.

The present invention has been made in view of the above problems, andhas an object of providing a packet communication method, a controllerdevice and a mobile station for being able to reduce the number of RLCconnections to be established, to improve performance in radiocommunication systems.

DISCLOSURE OF THE INVENTION

A first aspect of the present invention is summarized as comprising thesteps of establishing a radio layer 2 connection based on a radio layer2 protocol, between a mobile station and a controller device;determining a transmission timing of a received data packet, based on aquality of service set in the data packet; and multiplexing, at thedetermined transmission timing, the data packet into a radio layer 2protocol data unit of a fixed length which is transmitted and receivedon the radio layer 2 connection.

A second aspect of the present invention is summarized as a controllerdevice comprising a radio layer 2 connection establishing unitconfigured to establish, with a mobile station, a radio layer 2connection based on a radio layer 2 protocol; a transmission timingdetermining unit configured to determine a transmission timing of areceived data packet, based on a quality of service set in the datapacket; and a multiplexing unit configured to multiplex, at thedetermined transmission timing, the data packet into a radio layer 2protocol data unit of a fixed length which is transmitted and receivedon the radio layer 2 connection.

The second aspect of the present invention may further comprise atransmitting unit configured to transmit, by a transport technology, theradio layer 2 protocol data unit into which the data packet ismultiplexed.

A third aspect of the present invention is summarized as a mobilestation comprising a radio layer 2 connection establishing unitconfigured to establish, with a controller device, a radio layer 2connection based on a radio layer 2 protocol; a transmission timingdetermining unit configured to determine a transmission timing of areceived data packet, based on a quality of service set in the datapacket; and a multiplexing unit configured to multiplex, at thedetermined transmission timing, the data packet into a radio layer 2protocol data unit of a fixed length which is transmitted and receivedon the radio layer 2 connection.

The third aspect of the present invention may further comprise atransmitting unit configured to transmit, by a radio access technology,the radio layer 2 protocol data unit into which the data packet ismultiplexed.

A fourth aspect of the present invention is summarized as comprising thesteps of, at a mobile station, establishing a radio layer 2 connectionbased on a radio layer 2 protocol; establishing a plurality of tunnelingconnections between two or more controller devices; and at a firstcontroller device, referring to a terminal address included in a datapacket which is multiplexed on the radio layer 2 connection andtransmitted from the mobile station, and relaying the data packetthrough a tunneling connection associated with the terminal address.

In the fourth aspect of the present invention, the mobile station maytransmit a communication start request; the first controller device maytransmit a tunneling connection establishment request to a secondcontroller device in accordance with the communication start request;the second controller device may establish a tunneling connection withthe first controller device in accordance with the tunneling connectionestablishment request, and may associate the established tunnelingconnection with the terminal address; and the associated terminaladdress may be communicated to the mobile station.

A fifth aspect of the present invention is summarized as a controllerdevice comprising a tunneling connection establishing unit configured toestablish a plurality of tunneling connections with a certain controllerdevice; an associating unit configured to associate a terminal addressincluded in a data packet with a tunneling connection; a data packetreceiving unit configured to receive a data packet which is multiplexedon a radio layer 2 connection and transmitted from a mobile station; anda relay unit configured to refer to a terminal address included in thereceived data packet and relay the data packet through a tunnelingconnection associated with the terminal address.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an entire structural diagram of a radio communication systemfor implementing a packet communication method according to a relatedart;

FIGS. 2( a) to 2(c) are diagrams showing an example of a protocol stackfor implementing the packet communication method of the related art, andRLC connections and GTP connections established in the packetcommunication method of the related art;

FIG. 3 is an entire structural diagram of a radio communication systemfor implementing a packet communication method according to anembodiment of the present invention;

FIGS. 4( a) to 4(d) are diagrams showing protocol stacks forimplementing the packet communication method according to the embodimentof the present invention;

FIG. 5 is a functional block diagram of a radio network controlleraccording to the embodiment of the present invention;

FIGS. 6( a) and 6(b) are diagrams for illustrating the operation ofloading data packets in RLC-PDUs in the radio network controlleraccording to the embodiment of the present invention;

FIG. 7 is a diagram illustrating the way of loading data packets inMAC-PDUs in the packet communication methods according to the relatedart and the embodiment of the present invention;

FIG. 8 is a functional block diagram of a mobile station according tothe embodiment of the present invention;

FIG. 9 is a flowchart showing an operation for the radio networkcontroller to relay data packets in the packet communication methodaccording to the embodiment of the present invention;

FIG. 10 is a flowchart showing an operation for the mobile station torelay data packets in the packet communication method according to theembodiment of the present invention;

FIG. 11 is a diagram showing a protocol stack for implementing a packetcommunication method according to a modification of the presentinvention;

FIG. 12 is a functional block diagram of a subscriber node according tothe embodiment of the present invention;

FIG. 13 is a functional block diagram of a gateway node according to theembodiment of the present invention;

FIG. 14 is a sequence diagram showing the operation of associating a GTPconnection with a terminal address in the packet communication methodaccording to the embodiment of the present invention;

FIG. 15 is a sequence diagram showing the operation of relaying datapackets from a transmitting communication terminal to a receivingcommunication terminal in the packet communication method according tothe embodiment of the present invention;

FIG. 16 is a functional block diagram of a radio network controlleraccording to a modification 2 of the present invention;

FIG. 17 is a sequence diagram showing the operation of associating a GTPconnection with a terminal address in a packet communication methodaccording to the modification 2 of the present invention; and

FIG. 18 is a sequence diagram showing the operation of relaying datapackets from a transmitting communication terminal to a receivingcommunication terminal in the packet communication method according tothe modification 2 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

Hereinafter, a first embodiment of the present invention will bedescribed in detail with reference to the drawings. This embodiment willbe described with a focus on multiplexing a plurality of data packets inwhich different QoS requirements are set, on an RLC connectionestablished between a mobile station MS and a radio network controllerRNC.

As shown in FIG. 3, in a radio communication system according to thisembodiment, mobile networks are connected to an external packetcommunication network through a UMTS network. In each mobile network,communication terminals TE are connected to a mobile station MS, and areconfigured to be able to access the UMTS network via a radio interfaceof the mobile station MS.

In the UMTS network, base stations BS, a radio network controller RNC, asubscriber node SGSN, and a gateway node GGSN are disposed. Here, thesubscriber node SGSN is provided with an interface with the gateway nodeGGSN, and the gateway node GGSN is provided with interfaces with thesubscriber node SGSN and the packet communication network.

With reference to FIGS. 4( a) to 4(c), a protocol stack in the radiocommunication system according to this embodiment will be described.

As shown in FIG. 4( a), in the radio communication system according tothis embodiment, an RLC connection based on the RLC protocol, which isone of the radio layer 2 protocols, is established between the mobilestation MS and the radio network controller RNC.

Here, the radio layer 2 protocols are provided in layers higher than aphysical layer (L1) and transport technology layers (ATM/AAL/FP in theexample of FIG. 4( a)), and constituted by the Packet Data ConvergenceProtocol (PDCP), the RLC protocol, and the Medium Access Control (MAC)protocol.

The RLC protocol has the function of multiplexing and dividing datapackets (e.g., IP packets) received from an upper layer (e.g., the PDCPprotocol). An RLC-PDU used in the RLC protocol has a time length of 10ms. The byte length of an RLC-PDU is determined by the speed of an RLCconnection. For example, the byte length of an RLC-PDU on an RLCconnection set at a speed of 384 kbps is 480 bytes.

Also, when establishing an RLC connection, the RLC protocol determineswhich of Transparent Mode (TM), Unacknowledgement Mode (UM) andAcknowledgement Mode (AM) to provide to an upper layer.

Here, TM has the function of transferring a data packet received from anupper layer to a lower layer (MAC protocol) directly or after dividingit as necessary. TM also has the function of transferring data receivedfrom a lower layer to an upper layer directly or after composing it asnecessary.

UM and AM can divide or multiplex data packets received from an upperlayer to load into RLC-PDUs, and are suitable for transferringvariable-length data such as IP packets. RLC-PDUs are transferred to alower layer (a transport technology layer or a radio access technologylayer) through the MAC protocol. Here, UM does not have a dataretransmission function, while AM has the function of correcting anerror caused by quality deterioration in a radio zone by dataretransmission control.

Also, as shown in FIG. 4( a), in the radio communication systemaccording to this embodiment, an ATM connection of ATM Adaptation Layertype 2 (AAL2) is established by the ATM technology, one type oftransport technology, between the base station BS and the radio networkcontroller RNC.

As shown in FIG. 4( c), the radio communication system of thisembodiment may alternatively be configured so that communication isperformed by the IP technology, one type of transport technology,between the base station BS and the radio network controller RNC.

In the radio communication system of this embodiment, MAC-PDUs aretransmitted and received by the CDMA technology, one type of radioaccess technology, between the base station BS and the mobile stationMS.

In the radio communication system of this embodiment, for the mobilityof the communication terminals TE, a data packet transmitted from acommunication terminal TE and even having a destination address like anIP packet, is transferred on a tunneling connection (such as an ATMconnection, IP tunneling connection or MPLS connection) established by atransport technology.

This embodiment uses the RLC protocol specified in 3GPP as one of theradio layer 2 protocols, but may alternatively be configured to use theLAC protocol specified in 3GPP2.

FIG. 5 shows functional blocks of the radio network controller RNCaccording to this embodiment. As shown in FIG. 5, the radio networkcontroller RNC includes a data packet receiving unit 10, a QoS detectingunit 11, a transmission timing determining unit 12, a framing unit 17,and a transmitting unit 18.

The data packet receiving unit 10 is configured to receive data packetsthrough a GTP connection (tunneling connection) established with thegateway node GGSN based on the GTP protocol.

The QoS detecting unit 11 is configured to detect QoS requirements(qualities of service) set in data packets received by the data packetreceiving unit 10.

More specifically, the QoS detecting unit 11 is constituted by a QoSsorting unit 11 a which sorts data packets inputted from the data packetreceiving unit 10 into queues 121 to 12 n provided for QoS classes 1 ton, respectively, for input, according to QoS requirements set in thedata packets.

Here, a QoS requirement set in a data packet may be a “DifferentiatedServices Code Point (DSCP)” in an IP packet, for example.

The transmission timing determining unit 12 is constituted by the queues121 to 12 n and a scheduling unit 13.

The scheduling unit 13 is configured to sequentially output data packetsin the queues 121 to 12 n to the framing unit 17 by scheduling andpriority control based on a predetermined policy.

Specifically, the scheduling unit 13 is configured to determinetransmission timings of data packets in the queues 121 to 12 n, based onQoS requirements detected by the QoS detecting unit 11, and transmit thedata packets at the determined transmission timings to the framing unit17.

With reference to FIGS. 6( a) and 6(b), a specific example of operationof the scheduling unit 13 will be described. As shown in FIG. 6( a), forexample, the data packet receiving unit 10 receives two kinds of datapackets, a data packet in which high priority “H” is set as a QoSrequirement, and a data packet in which low priority “L” is set as a QoSrequirement.

In this case, as shown in FIG. 6( b), the scheduling unit 13 takescertain data packets at a determined transmission timing (taking timing)from the queues 121 to 12 n. Here, an RLC-PDU has a size of 1000 bytes,and a data packet has a size of 500 bytes. An RLC-PDU has a fixedlength. RLC-PDUs are transmitted at regular intervals.

As shown in FIG. 6( b), a data packet in which the high priority “H” isset is taken in priority to a data packet in which the low priority “L”is set. For example, a data packet of priority “H-2” which arrives laterthan a data packet of priority “L-3” is taken at transmission timing“F2”, and the data packet of priority “L-3” is kept queued untiltransmission timing “F3”.

The framing unit 17 is configured to multiplex data packets outputtedfrom the scheduling unit 13 into fixed-length radio layer 2 protocoldata units (RLC-PDUs), which are transmitted and received on a radiolayer 2 connection (RLC connection).

Specifically, the framing unit 17 is constituted by an RLC processingunit 14, an MAC/FP processing unit 15, and a transport technologyprocessing unit 16.

The RLC processing unit 14 is configured to multiplex and load a datapacket outputted from the scheduling unit 13 at the above transmissiontiming, partly or entirely into an RLC-PDU. The RLC processing unit 14is configured to perform PDCP protocol processing on the data packet asnecessary.

The MAC/FP processing unit 15 is configured to perform MAC protocolprocessing on an RLC-PDU generated by the RLC processing unit 14 togenerate an MAC-PDU. Also, the MAC/FP processing unit 15 is configuredto frame a generated MAC-PDU in an FP frame.

The transport technology processing unit 16 is configured to load an FPframe generated by the MAC/FP processing unit 15 in an ATM cell which istransmitted and received on an AAL2 ATM connection.

The transport technology processing unit 16 may alternatively beconfigured to load an FP frame generated by the MAC/FP processing unit15 in an IP packet which is transmitted and received on an IP tunnelingconnection, or in an IP packet which is transmitted and received on anMPLS connection. With reference to FIG. 7, a specific example ofoperation of the framing unit 17 in such a case will be described. Asshown in FIG. 7, the payload in an RLC-PDU has a fixed length, and datapackets in an upper layer have variable lengths. Therefore, data packetsshorter than the payload length of an RLC-PDU are multiplexed and loadedinto a single RLC-PDU. A data packet which cannot be loaded in a singleRLC-PDU is divided, and a part of it is loaded in the next RLC-PDU.

The transmitting unit 18 is configured to transmit an MAC-PDU loadedwith an RLC-PDU loaded with a data packet(s), through a radio layer 2connection (RLC connection) established based on a radio layer 2protocol (RLC protocol) with a mobile station MS.

The transmitting unit 18 is configured to perform QoS control in unitsof AAL2 ATM connections, using a traffic management technique in the ATMtechnology, on communication with a base station BS. The transmittingunit 18 may alternatively be configured to perform QoS control in unitsof IP tunneling connections (MPLS connections) or in units of IPpackets, using a traffic management technique in the IP technology, oncommunication with a base station BS.

FIG. 8 shows functional blocks of a mobile station MS according to thisembodiment. As shown in FIG. 8, the mobile station MS includes a datapacket receiving unit 20, a QoS detecting unit 21, a transmission timingdetermining unit 22, a framing unit 27, and a radio access communicationunit 28.

The mobile station MS of this embodiment has a configuration similar tothat of the above-described radio network controller RNC, except that atransport technology processing unit is not included in the framing unit27, and the radio access communication unit 28 is provided in place ofthe transmitting unit 18.

The radio access communication unit 28 is configured to transmitMAC-PDUs generated by an MAC processing unit 25 to a base station BS,using a radio access technology such as the CDMA technology.

Hereinafter, with reference to FIG. 9, an operation for the radionetwork controller RNC in this embodiment having the above configurationto perform transmission and reception of data packets will be described.

As shown in FIG. 9, in step S101, the data packet receiving unit 10 ofthe radio network controller RNC receives data packets from thesubscriber node SGSN.

In step S102, the QoS detecting unit 11 detects QoS requirements set inthe data packets received by the data packet receiving unit 10. InstepS103, the QoS sorting unit 11 a inputs the data packets into the queues121 to 12 n provided for different QoS classes, according to thedetected QoS requirements.

In step S104, the scheduling unit 13 sequentially outputs the datapackets sorted according to QoS, to the RLC processing unit 14 bypredetermined scheduling and priority control.

In step S105, the RLC processing unit 14 loads the data packetsoutputted from the scheduling unit 13 into RLC-PDUs. The length andtransmission intervals of RLC-PDUs are determined when an RLC connectionis established, and are fixed. RLC-PDUs are generated in conjunctionwith transmission timings determined at the scheduling unit 13. In thisembodiment, the timing of generating an RLC-PDU is not changed by thedata packet input traffic status.

When a space area is left in an RLC-PDU without any other data packet totransmit, the RLC-PDU is transmitted with the space area padded. Whenonly part of a data packet can be loaded in an RLC-PDU, the remainingpart of the data packet is loaded at the head of the payload of the nextRLC-PDU. When there is not any data packet to be loaded in an RLC-PDU,an RLC-PDU is not generated.

In step S106, the MAC/FP processing unit 15 performs MAC protocolprocessing on the generated RLC-PDUs (adding MAC headers as necessary),and frames them in FP frames. In an FP frame, one or more MAC-PDUs canbe loaded, depending on a transmission time interval (TTI) set when anRLC connection is established.

In step S107, the transport technology processing unit 16 loads thegenerated FP frames in ATM cells which are transmitted and received onan AAL2 ATM connection.

In step S108, the transmitting unit 18 transfers the generated ATMcells. Here, since there is the possibility that a data packet requiringa high quality of service is loaded in an RLC-PDU, the transporttechnology processing unit 16 transfers data packets at the highestquality of service RLC-PDUs handle.

Next, with reference to FIG. 10, an operation for a mobile station MS inthis embodiment having the above configuration to perform transmissionand reception of data packets will be described. Steps S201 to S205 aresimilar to steps S101 to S105 in FIG. 9.

In step S206, the MAC processing unit 25 performs MAC protocolprocessing on generated RLC-PDUs (adding MAC headers as necessary) togenerate MAC-PDUs.

In step S207, the radio access communication unit 28 transmits theMAC-PDUs generated by the MAC unit 25 to the base station BS using aradio access technology such as the CDMA technology.

According to the radio communication system of this embodiment, QoScontrol dealing with qualities of service required by data packets canbe performed in the RLC protocol, instead of in a transport technologysuch as the ATM technology or the IP technology, so that a delay in atunneling connection such as an ATM connection can be reduced.

In particular, in a UTRAN, synchronous control is performed usingsequence numbers in FP frames between a base station BS and a radionetwork controller RNC, and buffering is performed at a receiving endaccording to a maximum delay in FP frames. When QoS control in atransport technology causes large delay fluctuations in low-prioritycommunication, a delay according to the maximum delay occurs constantly.Therefore, it is also effective to implement low-delay transfer in atransport technology to reduce the buffer amount at a receiving end andto prevent occurrence of constant delays in low-priority communication.

Also, according to the radio communication system of this embodiment, amobile station MS can handle various communications by establishing asingle RLC connection without establishing an RLC connection for eachcommunication destination or QoS requirement.

[Modification 1]

In a modification 1 of the present invention, a base station BS isconfigured to include the functions of the radio network controller RNCshown in FIG. 5 to serve as a controller device in the presentinvention. FIG. 11 shows a protocol stack in a radio communicationsystem according to the modification 1.

As shown in FIG. 11, the modification 1 is configured so that an RLCconnection is established between a mobile station MS and a base stationBS, and a GTP connection is established between a base station BS and asubscriber node SGSN.

Second Embodiment

Next, a second embodiment of the present invention will be described.This embodiment will be described with a focus on an operation in theradio communication system according to the above-described firstembodiment when a transmitting communication terminal TE performingcertain communication with a receiving communication terminal TE startscommunication with a different QoS requirement or communication with adifferent receiving communication terminal.

A radio communication system according to this embodiment is configuredso that, as shown in FIG. 4( d), a radio network controller RNCassociates, one-to-one, an RLC connection established between a mobilestation MS and the radio network controller RNC with a GTP connectionestablished between the radio network controller RNC and a subscribernode SGSN, and the subscriber node SGSN associates a single GTPconnection established between the radio network controller RNC and thesubscriber node SGSN with a plurality of GTP connections establishedbetween the subscriber node SGSN and a gateway node GGSN.

As shown in FIG. 12, the subscriber node SGSN of this embodimentincludes an Activate PDP Context Request receiving unit 51, a Create PDPContext Request transmitting unit 52, a Create PDP Context Responsereceiving unit 53, a PDP context storage unit 54, an Activate PDPContext Response transmitting unit 55, and a data relay unit 56.

The Activate PDP Context Request receiving unit 51 is configured toreceive an Activate PDP Context Request transmitted from a mobilestation MS. The Activate PDP Context Request is for requesting start ofnew communication between a transmitting communication terminal TE and areceiving communication terminal TE, specifying a QoS requirement and acommunication destination.

The Create PDP Context Request transmitting unit 52 is configured toestablish a GTP connection (tunneling connection) with the gateway nodeGGSN in accordance with a received Activate PDP Context Request.

The Create PDP Context Response receiving unit 53 is configured toreceive a Create PDP Context Response and a terminal address transmittedfrom the gateway node GGSN. The terminal address may be included in theCreate PDP Context Response for transmission, or may be transmittedseparately from the Create PDP Context Response.

The PDP context storage unit 54 is configured to associate a terminaladdress included in a data packet transmitted from a mobile station MSthrough the radio network controller RNC with a GTP connection(tunneling connection), cooperating with the Activate PDP ContextRequest receiving unit 51 and the Create PDP Context Response receivingunit 53.

Specifically, as shown in FIG. 12, the PDP context storage unit 54 isconfigured to store a PDP context, an RNC-side GTP connection ID, aterminal address, and a GGSN-side GTP connection ID, which areassociated with one another.

The PDP context storage unit 54 stores a PDP context (e.g., QoSrequirement information and communication destination information)included in an Activate PDP Context Request received by the Activate PDPContext Request receiving unit 51.

The PDP context storage unit 54 also stores a GGSN-side GTP connectionID and a terminal address included in a Create PDP Context Responsereceived by the Create PDP Context Response receiving unit 53.

Here, the terminal address is an address (e.g., an IP address) used by atransmitting communication terminal TE in communication newly startedbetween the transmitting communication terminal TE and a receivingcommunication terminal TE, and may be assigned by the gateway node GGSNat the start of communication, or may be assigned fixedly to thetransmitting communication terminal TE.

The Activate PDP Context Response transmitting unit 55 is configured totransmit an Activate PDP Context Response to a mobile station MS througha GTP connection with the radio network controller RNC when detectingcompletion of establishment of a GTP connection between the subscribernode SGSN and the gateway node GGSN.

The data relay unit 56 is configured to extract a GGSN-side GTPconnection ID from the PDP context storage unit 54 based on a terminaladdress included in a data packet (GTP-PDU) transmitted from atransmitting communication terminal TE through a GTP connectionestablished with the radio network controller RNC, to transfer the datapacket to a GTP connection having the GGSN-side GTP connection ID.

The data relay unit 56 is also configured to extract an RNC-side GTPconnection ID from the PDP context storage unit 54 based on theGGSN-side GTP connection ID of a GTP connection established with thegateway node GGSN through which a data packet from a receivingcommunication terminal TE has passed, to transfer the data packet to aGTP connection having the RNC-side GTP connection ID.

As shown in FIG. 13, the gateway node GGSN in this embodiment includes aCreate PDP Context Request receiving unit 61, a terminal addressassigning unit 62, a PDP context storage unit 63, a Create PDP ContextResponse transmitting unit 64, and a data relay unit 65.

The Create PDP Context Request receiving unit 61 is configured toreceive a Create PDP Context Request transmitted from the subscribernode SGSN.

The terminal address assigning unit 62 is configured to assign aterminal address to be used by a transmitting communication terminal TEin newly started communication, in accordance with a Create PDP ContextRequest received by the Create PDP Context Request receiving unit 61.

For example, the terminal address assigning unit 62 may be configured toextract an unused address from a predefined address space to assign itas a terminal address, or may be configured to assign a terminal addressby negotiation with an external server device or the like.

The PDP context storage unit 63 is configured to create and store a PDPcontext related to newly started communication, in accordance with aCreate PDP Context Request received by the Create PDP Context Requestreceiving unit 61.

The Create PDP Context Response transmitting unit 64 is configured totransmit a Create PDP Context Response to the subscriber node SGSN as aresponse to a Create PDP Context Request.

The data relay unit 65 is configured to refer to the PDP context storageunit 63 to transfer a data packet transmitted from the subscriber nodeSGSN to the packet communication network. The data relay unit 65 is alsoconfigured to refer to the PDP context storage unit 63 to transfer adata packet transmitted from the packet communication network to thesubscriber node SGSN.

Hereinafter, with reference to FIG. 14, description will be made on anoperation in the radio communication system of this embodiment, in whichthe subscriber node SGSN and the gateway node GGSN, which haveestablished a single PDP context for communication of a mobile stationMS, establish a different PDP context due to a different QoS requirementor communication destination when the mobile station MS starts newcommunication.

As shown in FIG. 14, in step S201, the mobile station MS has establishedan RLC connection (radio access bearer) with the radio networkcontroller RNC. The radio network controller RNC has established a GTPconnection with the subscriber node SGSN.

In step S202, the mobile station MS transmits an Activate PDP ContextRequest to the subscriber node SGSN through the RLC connectionestablished with the radio network controller RNC.

In step S203, the Create PDP Context Request transmitting unit 52 of thesubscriber node SGSN transmits a Create PDP Context Request to thegateway node GGSN, in accordance with the Activate PDP Context Requestreceived by the Activate PDP Context Request receiving unit 51.

In step S204, the terminal address assigning unit 62 of the gateway nodeGGSN assigns a terminal address to be given to data packets to betransmitted and received in newly started communication, in accordancewith the Create PDP Context Request received by the Create PDP ContextRequest receiving unit 61.

In step S205, the Create PDP Context Response transmitting unit 64 ofthe gateway node GGSN communicates the terminal address assigned by theterminal address assigning unit 62, together with a Create PDP ContextResponse, to the subscriber node SGSN.

In step S206, the PDP context storage unit 54 of the subscriber nodeSGSN associates the terminal address communicated from the gateway nodeGGSN, the GGSN-side GTP connection ID of a GTP connection establishedwith the gateway node GGSN, and the RNC-side GTP connection ID of theGTP connection established with the radio network controller RNC.

Here, the subscriber node SGSN establishes the new GTP connection withthe gateway node GGSN according to the Create PDP Context Response fromthe gateway node GGSN. At this time, a GTP connection between thesubscriber node SGSN and the radio network controller RNC and an RLCconnection between the radio network controller RNC and the mobilestation MS are not newly established, and those established for anothercommunication (PDP context) are shared.

In step S207, the Activate PDP Context Response transmitting unit 55 ofthe subscriber node SGSN communicates, to the mobile station MS, theterminal address, together with an Activate PDP Context Response forcommunicating the fact that a PDP context for new communication has beencreated.

In step S208, the mobile station MS communicates the communicatedterminal address to a transmitting communication terminal TE asnecessary.

Next, with reference to FIG. 15, the operation of transferring datapackets from a transmitting terminal TE to a receiving terminal TE inthe radio communication system of this embodiment will be described.

As shown in FIG. 15, in step S301, a transmitting communication terminalTE transmits a data packet including, as a source address, a terminaladdress preassigned to the transmitting communicating terminal, andincluding, as a destination address, the address of a receivingcommunication terminal, to a mobile station MS in a mobile network.

In step S302, the mobile station MS multiplexes the received data packetinto an RLC-PDU as described in the above-described first embodiment. Instep S303, the mobile station MS transmits the RLC-PDU to the radionetwork controller RNC through an RLC connection established with theradio network controller RNC.

In step S304, the radio network controller RNC loads the data packetloaded in the received RLC-PDU in a GTP-PDU, and transmits it to thesubscriber node SGSN through a GTP connection established with thesubscriber node SGSN.

In step S305, the data relay unit 56 of the subscriber node SGSNextracts a GGSN-side GTP connection ID from the PDP context storage unit54 based on the terminal address included in the data packet loaded inthe received GTP-PDU. In step S306, the data relay unit 56 of thesubscriber node SGSN transmits the GTP-PDU loaded with the data packetto the gateway node GGSN through a GTP connection having the GGSN-sideGTP connection ID.

In step S307, the data relay unit 65 of the gateway node GGSN extractsthe data packet from the received GTP-PDU. In step S308, the data relayunit 65 of the gateway node GGSN transfers the extracted data packet tothe receiving communication terminal TE through the packet communicationnetwork.

[Modification 2]

A radio communication system according to a modification 2 of thepresent invention is configured so that, as shown in FIG. 4( b), a radionetwork controller RNC associates an RLC connection established betweena mobile station MS and the radio network controller RNC with aplurality of GTP connections established between the radio networkcontroller RNC and a subscriber node SGSN.

As shown in FIG. 16, the radio network controller RNC of themodification 2 includes a GTP connection establishing unit 71, an RLCconnection establishing unit 72, a storage unit 73, and a data relayunit 74.

The GTP connection establishing unit 71 is configured to establish a GTPconnection (tunneling connection) with the subscriber node SGSN inaccordance with a request from the subscriber node SGSN. The GTPconnection establishing unit 71 is also configured to receive a terminaladdress communicated from the subscriber node SGSN.

The RLC connection establishing unit 72 is configured to establish anRLC connection with a mobile station MS in accordance with a requestfrom the mobile station MS. The RLC connection establishing unit 72 mayalternatively be configured to use an RLC connection which has alreadybeen established with a mobile station without establishing a new RLCconnection, even when receiving a request from the mobile station MS.

Also, the RLC connection establishing unit 72 communicates a terminaladdress communicated from the subscriber node SGSN to a mobile stationMS through an RLC connection established with the mobile station MS.

The storage unit 73 is configured to associate a terminal addressincluded in a data packet transmitted from a mobile station MS with aGTP connection (tunneling connection), cooperating with the RLCconnection establishing unit 72 and the GTP connection establishing unit71.

Specifically, as shown in FIG. 16, the storage unit 73 is configured tostore an AAL2 connection ID corresponding to an RLC connection, aterminal address, and a GTP connection ID, which are associated with oneanother.

The storage unit 73 also stores the GTP connection ID of a GTPconnection established by the GTP connection establishing unit 71, and aterminal address received by the GTP connection establishing unit 71.

Here, the terminal address is an address (e.g., IP address) used by atransmitting communication terminal TE in communication newly startedbetween the transmitting communication terminal TE and a receivingcommunicating terminal TE, and may be the one assigned by the gatewaynode GGSN at the start of communication, or may be the one assignedfixedly to the transmitting communication terminal TE.

The data relay unit 74 is configured to extract a GTP connection ID fromthe storage unit 75 based on a terminal address included in a datapacket (GTP-PDU) transmitted from a transmitting communication terminalTE through an RLC connection established with a mobile station MS, andtransfer the data packet to a GTP connection having the GTP connectionID.

The data relay unit 77 is also configured to extract an AAL2 connectionID from the storage unit 73 based on the GTP connection ID of a GTPconnection established with the subscriber node SGSN through which adata packet from a receiving communication terminal TE has passed, andtransfer the data packet to an RLC connection corresponding to an AAL2connection having the AAL2 connection ID.

The gateway node GGSN according to the modification 2 is similar inconfiguration to the gateway node according to the second embodimentshown in FIG. 13.

Hereinafter, with reference to FIG. 17, description will be made on anoperation in the radio communication system of the modification 2, inwhich the subscriber node SGSN and the gateway node GGSN, which haveestablished a PDP context for communication of a mobile station MS,establishes a different PDP context due to a different QoS requirementor communication destination when the mobile station MS starts newcommunication.

As shown in FIG. 17, in step S401, the mobile station MS transmits anActivate PDP Context Request to the subscriber node SGSN when receivinga data packet addressed to a packet communication network from atransmitting communication terminal TE in a mobile network.

In step S402, the subscriber node SGSN transmits a Create PDP ContextRequest to the gateway node GGSN in accordance with the receivedActivate PDP Context Request, thereby performing GTP connectionestablishment processing with the gateway node GGSN. Specifically, thesubscriber node SGSN and the gateway node GGSN perform the process ofsteps S203 to S206 shown in FIG. 14.

In step S403, the subscriber node SGSN transmits an Activate PDP ContextResponse to the mobile station MS.

In step S404, the GTP connection establishing unit 71 of the radionetwork controller RNC performs GTP connection establishment processingwith the subscriber node SGSN in accordance with a request from thesubscriber node SGSN. Here, the subscriber node SGSN communicates aterminal address communicated from the gateway node to the radio networkcontroller RNC.

In step S405, the storage unit 75 of the radio network controller RNCassociates the terminal address communicated from the subscriber nodeSGSN, the GTP connection ID of a GTP connection established with thesubscriber node SGSN, and the AAL2 connection ID of an AAL2 connectioncorresponding to an RNC connection established with the mobile stationMS.

In step S406, when an RLC connection (radio access bearer) has not beenestablished with the mobile station MS, the RLC connection establishingunit 72 of the radio network controller RNC establishes an RLCconnection.

In step S407, the mobile station MS communicates the communicatedterminal address to the transmitting communication terminal TE asnecessary.

Next, with reference to FIG. 18, the operation of transferring datapackets from a transmitting terminal TE to a receiving terminal TE inthe radio communication system of the modification 2 will be described.

As shown in FIG. 18, in step S501, a transmitting communication terminalTE transmits a data packet including, as a source address, a terminaladdress preassigned to the transmitting communication terminal, andincluding, as a destination address, the address of a receivingcommunication terminal, to a mobile station MS in a mobile network.

In step S502, the mobile station MS multiplexes the received data packetinto an RLC-PDU as described in the first embodiment. In step S503, themobile station MS transmits the RLC-PDU to the radio network controllerRNC through an RLC connection established with the radio networkcontroller RNC.

In step S504, the data relay unit 77 of the radio network controller RNCextracts a GTP connection ID from the storage unit 75 based on theterminal address included in the data packet loaded in the receivedRLC-PDU. In step S505, the data relay unit 77 of the radio networkcontroller RNC transmits a GTP-PDU loaded with the data packet to thesubscriber node SGSN through a GTP connection having the GTP connectionID.

In step S506, the subscriber node SGSN transfers the GTP-PDU to a GTPconnection established with the gateway node GGSN which is associatedwith the GTP connection established with the radio network controllerRNC through which the received GTP-PDU has passed.

In step S507, the data relay unit 65 of the gateway node GGSN extractsthe data packet from the received GTP-PDU. In step S508, the data relayunit 65 of the gateway node GGSN transfers the extracted data packet tothe receiving communication terminal TE through the packet communicationnetwork.

INDUSTRIAL APPLICABILITY

According to the present invention, the number of RLC connections to beestablished can be reduced, and loads related to path changes inhandovers can be reduced.

1. A packet communication method comprising the steps of: establishing asingle radio layer 2 connection based on a radio layer 2 protocol,between a mobile station and a controller device, the single radio layer2 connection associated with multiple GTP (GPRS Tunneling Protocol)based connections; receiving, at the controller device, data packets inwhich respective qualities of service are set; inputting, at thecontroller device, the data packets to queues corresponding to therespective qualities of service; determining, at the controller device,a timing for taking out each data packet of the data packets from thequeues corresponding to the respective qualities of service, based onthe respective qualities of service; and multiplexing, at the controllerdevice, each data packet of the data packets taken from the queues atthe determined timing into a radio layer 2 protocol data unit of a fixedlength which is transmitted and received on the single radio layer 2connection associated with multiple GTP based connections.
 2. Acontroller device comprising: a radio layer 2 connection establishingunit configured to establish, with a mobile station, a single radiolayer 2 connection based on a radio layer 2 protocol, the single radiolayer 2 connection associated with multiple GTP (GPRS TunnelingProtocol) based connections; a reception unit configured to receive aplurality of data packets in which respective qualities of service areset; an input unit configured to input the plurality of data packets toqueues corresponding to the respective qualities of service; atransmission timing determining unit configured to determine a timingfor taking out each data packet of the plurality of data packets fromthe queues corresponding to the respective qualities of service, basedon the respective qualities of service; and a multiplexing unitconfigured to multiplex each data packet of the plurality of data packetpackets taken from the queues at the determined timing into a radiolayer 2 protocol data unit of a fixed length which is transmitted andreceived on the single radio layer 2 connection associated with multipleGTP based connections.
 3. The controller device as set forth in claim 2further comprising, a transmitting unit configured to transmit, by atransport technology, the radio layer 2 protocol data unit into whicheach data packet of the plurality of data packets is multiplexed.
 4. Amobile station comprising: a radio layer 2 connection establishing unitconfigured to establish, with a controller device, a single radio layer2 connection based on a radio layer 2 protocol, the single radio layer 2connection associated with multiple GTP (GPRS Tunneling Protocol) basedconnections; an input unit configured to input a plurality of datapackets, in which respective qualities of service are set, to queuescorresponding to the respective qualities of service; a transmissiontiming determining unit configured to determine a timing for taking outeach data packet of the plurality of data packets from the queuescorresponding to the respective qualities of service, based on therespective qualities of service; and a multiplexing unit configured tomultiplex, each data packet of the plurality of data packets taken fromthe queues at the determined timing into a radio layer 2 protocol dataunit of a fixed length which is transmitted and received on the singleradio layer 2 connection associated with multiple GTP based connections.5. The mobile station as set forth in claim 4 further comprising, atransmitting unit configured to transmit, by a radio access technology,the radio layer 2 protocol data unit into which each data packet of theplurality of data packet packets is multiplexed.
 6. A packetcommunication method comprising: establishing, at a mobile station, asingle radio layer 2 connection based on a radio layer 2 protocol;establishing a plurality of GTP (GPRS Tunneling Protocol) basedtunneling connections for respective qualities of service, between afirst controller device and a second controller device; receiving, atthe first controller device, a plurality of data packets in which therespective qualities of service are set and which are transmitted fromthe mobile station, through the single radio layer 2 connection or asingle GTP based tunneling connection; determining, at the firstcontroller device, a GTP based tunneling connection associated with aterminal address of the mobile station and a quality of service whichare included in each data packet of the received plurality of datapackets, among a plurality of GTP based tunneling connections forrespective qualities of service; and relaying, at the first controllerdevice, each data packet of the plurality of data packets to the secondcontroller device through the determined GTP based tunneling connection.7. The packet communication method as set forth in claim 6 furthercomprising the steps of: transmitting, at the mobile station, acommunication start request; transmitting, at the first controllerdevice, a GTP (GPRS Tunneling Protocol) based tunneling connectionestablishment request to the second controller device in accordance withthe communication start request; establishing, at the second controllerdevice, a GTP based tunneling connection with the first controllerdevice in accordance with the GTP based tunneling connectionestablishment request, and associating the established GTP basedtunneling connection with the terminal address of the mobile station;and communicating the associated terminal address to the mobile station.8. A controller device comprising: a tunneling connection establishingunit configured to establish a plurality of GTP (GPRS TunnelingProtocol) based tunneling connections for respective qualities ofservice with a certain controller device; a data packet receiving unitconfigured to receive a plurality of data packets in which therespective qualities of service are set and which are transmitted from amobile station, through a single radio layer 2 connection or a singleGTP based tunneling connection; and a relay unit configured to determinea GTP based tunneling connection associated with a terminal address ofthe mobile station and a quality of service which are included in eachdata packet of the received plurality of data packets, among a pluralityof GTP based tunneling connections for respective qualities of service,and to relay each data packet of the plurality of data packets to thesecond controller device through the determined GTP based tunnelingconnection.